Teladorsagia

Question 1

Which two species of nematodes predominantly cause parasitic gastro-enteritis in sheep?

Answer 1

• Teladorsagia circumcincta

- Trichostrongylus spp

Question 2

Where in the GI tract is PGE found?

Answer 2

Abomasum

Small intestine

Question 3

Why is the location of PGE in the GI tract important?

Answer 3

• identification of the nematode

- disease pathology

Question 4

If there is PGE in the abomasum which nematodes could be causing it?

Answer 4

• Teladorsagia circumcincta

- Trichostrongylus axei

Question 5

If there is PGE in the small intestine which nematodes could be causing it?

Answer 5

• Cooperia spp

- Trichostrongylus spp

Question 6

Describe the morphology of adult T.Circumcincta worm

Answer 6

• 1cm in length
• slender, pinky-brown colour
• male and female
• fine cervical papillae at the head end, tiny indentations on the cuticle
• males have a bursa and spiracles at tail end

Question 7

What is hypobiosis?

Answer 7

Arrested development of larvae within the host

Question 8

Describe life cycle 1 of trichostrongyle

Answer 8

• Free living stages on pasture in the environment
• Parasitic stages in host
• Larval stage also in host
• Direct: no intermediate host

Question 9

Describe life cycle 2 of trichostrongyle

Answer 9

• Adult worms in abomasum

- Mate and females produce eggs

Question 10

Describe life cycle 3 of trichostrongyle

Answer 10

• Eggs develop in faecal pat, first stage larval in egg (L1) and then hatch
• Feed on bacteria, grows and moults into L2
• L2 moults into L3 which is ensheathed
• L3 released from faecal pat by rain splash

Question 11

Which stage of Trichostrongyle is the infective stage?

Answer 11

L3

Question 12

Describe life cycle 4 of trichostrongyle

Answer 12

• Sheep eat L3 as they graze, they are swallowed and reach abomasum
• Burrow into gastric glands
• Develops into L4 and L5
• L5 are immature adults which emerge into the abomasum lumen where they mature

Question 13

What is the pre-patent period?

Answer 13

Time taken from the time of infection (ingesting L3) to the detection of eggs in the faeces
- 3 weeks in sheep

Question 14

What is the trigger for hypobiosis?

Answer 14

• Drop in ambient temperature in the autumn

- stimulates L3 to hypobiose when ingested

Question 15

What are the functions of the gastric glands?

Answer 15

• Maintains acid pH in abomasum
• Bacteriostatic
• Converts pepsinogen to pepsin

Question 16

Describe the pathogenic steps of PGE

Answer 16

1. Larvae (L4 and L5) develop in gastric glands
2. Damage glands
3. Parietal cells replaced by undifferentiated epithelial cells
4. Loss of acid production
5. Increase in abomasal pH
6. Loss of bacteriostatic effect
7. No conversion of pepsinogen to pepsin
8. Increased permeability of mucosa

Question 17

What are the clinical signs of PGE disease - type 1?

Answer 17

• Profuse watery diarrhoea
• Weight loss
• Inappetence
• Dehydration
• Death

Question 18

Who is affected by type 1 PGE disease and when does disease occur?

Answer 18

First season grazing lambs

Mid-summer onwards

Question 19

Describe type 2 PGE including, who it affects and when

Answer 19

• Hypobiosed larvae are present within the abomasum (T. circumcincta)
• Simultaneous emergence of L5 – DISEASE
• Yearling animals
• Late winter/early spring